1. Field of the Invention
The invention relates in general to a display apparatus, and more particularly to a display driving circuit and the method thereof.
2. Description of the Related Art
A display apparatus, which converts digital video signals of a computer into a visually recognizable image, serves as an interface between a user and a computer. FIG. 1 is a block diagram of a familiar display apparatus. Display apparatus 100 uses a liquid crystal display apparatus as an example here. The display apparatus 100 includes a display driving circuit 110 and a display panel 180. The display driving circuit 110 includes a color correction unit 120, a data inversion unit 140 and a driving unit 160. The color correction unit 120 receives a digital video signal PD and performs color correction on the digital video signal PD, then outputs the color corrected video signal PD′ to the data inversion unit 140. The data inversion unit 140 either selectively inverts or maintains the color corrected video signal PD′, then outputs a polarity digital video signal PD″ accordingly. After receiving the polarity digital video signal PD″, the driving unit 160 performs digital-to-analog inversion on polarity digital video signal PD″, then outputs an analog driving voltage Vpd. After that, the display panel 180 displays a frame on the display panel according to the analog driving voltage Vpd.
Color correction is for correcting the characteristics of the inputted digital video signals to achieve a better color quality when the digital video signals are displayed on the frame. Take the liquid crystal display panel for example: the relationship between the gray value of an ordinary liquid crystal display panel and the driving voltage is non-linear, so color correction is needed. The non-linear curve is also called a ‘color corrected curve’ or a ‘gamma curve’, while the ‘color correction’ is also called ‘gamma correction’.
FIG. 2 is a diagram of a familiar color corrected curve. The x-axis is the inputted digital video signal PD while the y-axis is the outputted color corrected video signal PD′. The digital video signal PD generates a corresponding color corrected video signal PD′ in accordance with the color corrected curve. The driving unit 160 outputs an analog driving voltage Vpd according to the received color corrected video signal PD′ so that the display panel 180 displays a correct frame on the display panel.
The liquid crystal molecules of a liquid crystal display apparatus will be easily electrically inferior when exposed to the driving voltage of the same polarity for long. To resolve the inferiority problem, a familiar technology uses the positive driving voltage alternating with the negative driving voltage to drive the liquid crystal molecules. The data inversion unit 140 is for determining the driving polarity of the polarity video signal PD″. After having been processed by the driving unit 160, the positive video signal PD″ is outputted as a positive analog driving voltage Vpd, while the negative digital video signal PD″ is outputted as a negative analog driving voltage Vpd.